Programming Forums - Command line screen capture

Anyone know of any useful apps to capture screen to compressed JPG (compression can be set)

I have tried this code in Autoit:

; Capture full screen
; Fist parameter - filename, last - jpeg quality. 
DllCall("captdll.dll", "int", "CaptureScreen", "str", "dump_full.jpg", "int", 85)
; Capture given region
; Fist parameter - filename, next four: left, top, width, height. Last one - jpeg quality.
; Set quality to any negative number to capture into BMP
DllCall("captdll.dll", "int", "CaptureRegion", "str", "dump_partial.bmp", "int", 100, "int", 100, "int", 300, "int", 200, "int", -1)

and it does save the JPG but gives up an error like this:
AutoIT has detected the stack has become corrupt.
Obviously some sort of problem with the DLL

but if there's code for this in C or C++ or BASIC or anything that anyone has, I'll take it.... This application would be extremely useful for our I.T. Department.

Any help is much appreciated. Thanks for reading